Dry compressor



Dec. 26, 1967 A. VAN HEES 3,360,192

DRY COMPRESSOR Filed Aug. 24, 1965 I 5 Sheets-Sheet 1 FIG. I,

IN VEN TOR.

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INVENTOR.

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INVENTOR. /?/fl/V VIA/#555) United States Patent 3,360,192 DRY COMPRESSOR Adrian Van Hees, Harksheide, Holsatia, Germany, assiguor to Claudius Peters, AG., Hamburg, Germany Filed Aug. 24, 1965, Ser. No. 482,108 Claims. (Cl. 230-152) ABSTRACT OF THE DISCLOSURE A dry compressor having a lubricant circulating system for the bearings and a passageway between the rotating blades and bearings in order to provide communication with a zone of a pressure lower than the pressure about the rotating blades.

The present invention relates to the pumping of fluids, and is more particularly concerned with a compressor for gases which avoids contamination of the gases by lubricants.

Previous rotary sliding-vane designs are known which try to avoid the need for direct lubrication of the vanes or blades by using shrouds rotating with the cylinder and carrying the outer edges of the blades. These have not been entirely satisfactory as dry-operating designs, mainly because of the difficulty in sealing the working chambers or pockets from penetration by oil from the oil-washed bearing chambers.

The present invention provides a compressor eliminating this problem by providing a flushing-gap or passageway between the stationary housing and the rotating shroud or part rotating therewith. The flushing passageway communicates with a zone of lower pressure than the pressure about the shroud, and preferably with a chamber vented to the atmosphere. 1

Preferably, the bearings for the rotating shrouds are adjustably mounted in shouldered bearing carriers, while the flushing passageway is provided with a width slightly greater than the bearing play between the shroud and the bearing carrier.

A preferred feature of the invention is that the bearing chamber, exterior of the passageway, drains through a port and into the bearing-oil reservoir, which is, in turn, vented to the atmosphere, to maintain a lower pressure exterior of the passageway.

A better understanding of the invention may be derived from the following description and the accompanying drawings, in which:

FIG. 1 is a sectional view taken longitudinally through the machine;

FIG. 2 is a sectional view taken along lines 11-11 of FIG. 1, and

FIG. 3 is an isometric view of a portion of the machine with portions cut away.

As shown in the drawings, the preferred form of compressor according to the invention comprises a casing 1 having an inlet 2 and an outlet 3 therein.

The casing has a central bore 4 with which the inlet and outlet communicate. Eccentrically positioned in the lower portion of the bore 4, a slotted cylindrical rotor 5 carrying sliding vanes or blades 6 separates the inlet and outlet. The shaft 7 of the rotor 5 is carried in suitable bearings 8 and 9 mounted in casing end covers 10 and 11, respectively.

A pair of shrouds 12, 13 each enclose one end of the rotor 5, with the shaft 7 of the rotor extending through the hollow axles 14 and 15 of the shrouds. The shroud axles 14 and 15 are carried in bearings 16, 17, respectively mounted in bearing carriers 18 and 19. The carriers ice 18 and 19 are held in bores 20 and 21, respectively, in the end covers 10 and 11.

The bearing carriers 18 and 19 each have a shoulder 22, 23, respectively, to limit the inward position of their bearings toward the rotor 5, and means such as a snap ring 24, 25 to secure the bearings outer race against its shoulder 22, 23.

The bearing carriers 18 and 19 each have a peripheral drain groove 26, 27, with a plurality of drain ports 26, 27' leading from the interior of the carrier to the respective drain groove.

The shrouds 12 and 13 each have a shoulder 28, 29 against which the inner race of their respective bearing is secured by clamp rings 30 and 31 respectively.

The bearing carrier shoulders 22, 23 and shroud shoulders 28, 29 are'selected in relative diameters providing for an annular passageway 32 between the assembly 22/28 and an annular passageway 33 between the assembly 23/29.

The passageways 32 and 33 respectively communicate with the end clearance chambers 34, 35 between the shrouds and'the end covers. These chambers 34, 35 are, in turn, in communcat'ion with the running clearance zones 36, 37 about the outer surfaces of the. shrouds.

The radial width of the passageways 32, 33 should be selected to be greater than the bearing play-of the bearings 16 and 17 to prevent closure of portions of the passageways. Adjustable structures would be appropriatein dimensioning the passageways. The axial width of the clearance chambers 34 and 35 depend upon the spacing of the two shrouds with respect to each other.

The shrouds are limited in their travel toward each other by engagement with the interposed rotor 5. The rotor 5 carries a seal ring 38, 38' at each end-With suitable biasing means to provide a seal against leakage of gas from the rotor pockets toward the interior of the. shroud axles. The shrouds are positioned against outward movement away from each other preferably by selectableposition means such as adjusting screws or shims 39, 40.

Running clearances are to be maintained between the shrouds and all adjacent, stationary portions of the casing and end covers.

The internal diameters of the shrouds 13, 14 are equal to each other and slightly less than the diameter of the bore 4 in casing 1. The shrouds then carry the outer edges of the blades 6 in a running-clearance relationship with the bore 4 to avoid frictional contact of the blades with the casing.

Frictional contact between the shrouds and the blades 6 of the driven rotor is relied upon to drive the shrouds at a speed similar to the rotor speed thereby minimizing wear and, with the running clearance between the blades and the bore 4, avoiding the need for direct lubrication of the blades and compression pockets.

The bearing lubrication system comprises a pump 41 arranged to draw a lubricant such as oil from a reservoir 42 and deliver it via conduits 43 and 44 to the chambers 45 and 46 of bearings 8 and 9, respectively. The oil then drains from chambers 45, 46 into bearing chambers 47, 48 housing bearings 16 and 17, respectively.

Drain conduits 49 and 50 communicate with the chambers 47 and 48 each at a point in the lower region thereof and open to its respective drain groove 26, 27 in the bearing carrier. The drain conduits 49 and 50 lead back to the reservoir 42. The reservoir is provided with means to maintain a substantially lower pressure therein than will occur in the clearance chambers 34 and 35, such as the atmospheric vent 51 shown in FIG. 1.

In operation, the shaft of rotor 5 is driven rotationally by suitable means not shown. Centrifugal force drives the blades outwardly against the shrouds 12, 13 to form compression pockets successively registering with first the inlet 2 and then the outlet 3, with intermediate compression of the pockets and the air or gas therein for discharge through the outlet.

Frictional engagement between the rotor, blades and shrouds causes a similar rotation of the shrouds 12, 13 which are free to rotate on their axles 14, 15 Within bearings 16 and 17.

The ends of the pockets are sealed inwardly by the seal rings 38, 38. However, the running clearance zones 36 and 37-by communicating with the bearing chambers 47, 48 via clearance chambers 34, 35 and passageways 32, 33-allow a designed amount of compressed air to escape toward both bearing chambers 47 and 48. Since the bearing chambers 47, 48 are in communication with the atmosphere, via drain parts 26', .27 and the reservoir vent 51, the escape of air from the compression pockets is continuous.

Therefore, a sweeping current of the air or gas being compressed is maintained through the clearance chambers, the passageways, the drain ports, the drain grooves and the drain conduits to the reservoir, and ultimately to atmosphere. Any oil which flows from a bearing chamber toward the rotor and its compression pockets is thus swept away from that area back toward the bearings and then into the reservoir. This flow restricts the oil level in the bearing chambers to prevent flooding, without blocking adequate lubrication.

Various changes may be made in the details of the invention as described without sacrificing the advantages thereof or departing from the scope of the appended claims.

I claim:

1. A compressor having a casing, fluid inlet and discharge means for the casing, a rotating member, bearing means, lubricating means for the bearing means, a source supplying a lubricant to the bearing means, a shroud positioned between the rotating member and the bearing means, said shroud being mounted for engagement with and rotating with the rotating member, a stationary member surrounding a portion of said shroud and closely spaced therewith to form a passageway therebetween from the rotating member to the bearing means, the remainder of said shroud being sized to provide a running clearance with adjacent stationary members, a lubricant drain for the bearing means, said lubricant drain communicating with a zone of a pressure lower than the pressure about the shroud and means for directing gas escaping said rotating member adjacent said shro d to pass through said passageway in a direction away from the rotating member and shroud.

2. A compressor according to claim 1 in which the lubricant source comprises a lubricant reservoir, said reservoir supplying lubricant to the bearing means via a pump means, said reservoir being vented to the atmosphere and said lubricant drain communicating with said reservoir.

3. A compressor as set forth in claim 2 in which the rotating member comprises a slotted rotor having radiallysliding blades therein, and said shroud is positioned to enclose at least a portion of the outer edges of the blades.

4. A compressor as set forth in claim 2 in which the passageway is positioned between that portion of the shroud enclosing the blades and the bearing means.

5. A compressor according to claim 2 in which the shroud has an axle mounted in bearings, and the passageway is provided in a dimension slightly greater than the bearing play of the shroud-axle bearings.

References Cited UNITED STATES PATENTS 1,441,375 1/1923 Rolalf 230-152 1,776,921 9/1930 Moessinger 230-152 2,324,903 7/1943 Beckman 230-152 2,367,326 1/1945 Beckman 230-153 2,414,187 l/19-47 Borsting 230-152 2,791,184 5/1957 Sturm 103-121 2,818,707 1/1958 Sturm 103-121 2,988,007 6/1961 Quintilian 103-121 DONLEY J. STOCKING, Primary Examiner.

WILBUR J. GOODLIN, Examiner. 

1. A COMPRESSOR HAVING A CASING, FLUID INLET AND DISCHARGE MEANS FOR THE CASING, A ROTATING MEMBER, BEARING MEANS, LUBRICATING MEANS FOR THE BEARING MEANS, A SOURCE SUPPLYING A LUBRICANT TO THE BEARING MEANS, A SHROUD POSITIONED BETWEEN THE ROTATING MEMBER AND THE BEARING MEANS, SAID SHROUD BEING MOUNTED FOR ENGAGEMENT WITH AND ROTATING WITH THE ROTATING MEMBER, A STATIONARY MEMBER SURROUNDING A PORTION OF SAID SHROUD AND CLOSELY SPACED THERWITH TO FORM A PASSAGEWAY THEREBETWEEN FROM THE ROTATING MEMBER TO THE BEARING MEANS, THE REMAINDER OF SAID SHROUD BEING SIZED TO PROVIDE A RUNNING CLEARANCE WITH ADJACENT STATIONARY MEMBERS, A LUBRICANT DRAIN FOR THE BEARING MEANS, SAID LUBRICANT DRAIN COMMUNICATING WITH A ZONE OF A PRESSURE LOWER THAN THE PRESSURE ABOUT THE SHROUD AND MEANS FOR DIRECTING GAS ESCAPING SAID ROTATING MEMBER ADJACENT SAID SHROUD TO PASS THROUGH SAID PASSAGEWAY IN A DIRECTION AWAY FROM THE ROTATING MEMBER AND SHROUD. 